Loss of telomeres limits the lifespan of human cells and thus greatly impedes the ability of mammalian tissues to be manipulated for the purposes of, for example, tissue engineering. It has been demonstrated that ectopic expression of hTERT (the catalytic protein subunit of human telomerase reverse transcriptase) in human cells can arrest telomere shortening and immortalize cells. However, sustained expression of hTERT can promote tumor growth. Thus, use in humans of cells manipulated by sustained expression of hTERT raises concerns relating to the induction of tumorigenic growth of manipulated cells. This problem could be overcome by transient expression of hTERT, however, transient expression may not result in sufficient elongation of telomeres to provide for extended culturing.
The present invention provides a safe and efficient method of elongating telomere length of cells, e.g., cultured human cells. The method makes possible, for example, a variety of tissue engineering techniques.